The purpose of the Flow Cytometry and Functional Immunology Research Core is to provide a centralized resource of technical expertise and major equipment to support and enhance the experimental design and execution of basic and clinical research in HIV pathogenesis that require application of flow cytometric phenotypic analysis, cell sorting, and/or evaluation of specific immune cell functions. A prime goal is to provide the intellectual environment and the material resources to enable junior investigators to apply flow cytometry technology to their projects and to encourage established investigators to initiate innovative pilot studies. To achieve these objectives, expert consultation is provided through the Core Director, Associate Directors, and technical supervisor; major instruments are selected for complementary functions; equipment use is accessible through dedicated technician operators; services are provided on a recharge basis; generated data are analyzed, reduced, and diagramed; and fiscal support is given to pilot and exploratory research projects through the provision of research reagents and instrument time. CFAR resources have enabled the Core to support a wide array of HIV research encompassing basic projects on viral regulation and mechanisms of pathogenesis to preclinical development of vaccines and gene therapies, and clinical studies of primary infection, opportunistic infections, neurobiology, and immune and viral responses to vaccines and HAART. To maintain our flow cytometry facility to meet the needs of the San Diego academic research community, several funding sources have been integrated for cooperative support: the UCSD Center for AIDS Research (CFAR), the VA Research Center for AIDS and HIV Infection (RCAHI), and the Veterans Affairs Medical Research Foundation (VMRF). In addition to principal investigators based at UCSD and the VA Medical Center, investigators from The Scripps Research Institute, the Salk Institute, the La Jolla Institute of Allergy and Immunology, and the Burnham Institute also utilize the resources provided by our central facility. Local use of flow cytometric technology continues to grow and diversify, and the Core facility strives to keep up with the growing demand. The CFAR award remains an integral component in this endeavor. Application of flow cytometry to several areas of biomolecular research, in addition to expanded applications in clinical research, makes continued CFAR support crucial to providing the infrastructure to take advantage of new scientific opportunities in HIV research.